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In a burning plasma state1–7, alpha particles from deuterium–tritium fusion reactions redeposit their energy and are the dominant source of heating. This state has recently been achieved at the US National Ignition Facility8using indirect-drive inertial-confinement fusion. Our experiments use a laser-generated radiation-filled cavity (a hohlraum) to spherically implode capsules containing deuterium and tritium fuel in a central hot spot where the fusion reactions occur. We have developed more efficient hohlraums to implode larger fusion targets compared with previous experiments9,10. This delivered more energy to the hot spot, whereas other parameters were optimized to maintain the high pressures required for inertial-confinement fusion. We also report improvements in implosion symmetry control by moving energy between the laser beams11–16and designing advanced hohlraum geometry17that allows for these larger implosions to be driven at the present laser energy and power capability of the National Ignition Facility. These design changes resulted in fusion powers of 1.5 petawatts, greater than the input power of the laser, and 170 kJ of fusion energy18,19. Radiation hydrodynamics simulations20,21show energy deposition by alpha particles as the dominant term in the hot-spot energy balance, indicative of a burning plasma state.

Obtaining a burning plasma is a critical step towards self-sustaining fusion energy1. A burning plasma is one in which the fusion reactions themselves are the primary source of heating in the plasma, which is necessary to sustain and propagate the burn, enabling high energy gain. After decades of fusion research, here we achieve a burning-plasma state in the laboratory. These experiments were conducted at the US National Ignition Facility, a laser facility delivering up to 1.9 megajoules of energy in pulses with peak powers up to 500 terawatts. We use the lasers to generate X-rays in a radiation cavity to indirectly drive a fuel-containing capsule via the X-ray ablation pressure, which results in the implosion process compressing and heating the fuel via mechanical work. The burning-plasma state was created using a strategy to increase the spatial scale of the capsule2,3through two different implosion concepts4–7. These experiments show fusion self-heating in excess of the mechanical work injected into the implosions, satisfying several burning-plasma metrics3,8. Additionally, we describe a subset of experiments that appear to have crossed the static self-heating boundary, where fusion heating surpasses the energy losses from radiation and conduction. These results provide an opportunity to study α-particle-dominated plasmas and burning-plasma physics in the laboratory.

Objective.To compare the effectiveness for prevention of central venous and arterial catheter colonization of 3 skin antisepsis with 1 of 3 antiseptic solutions: 10% aqueous povidone iodine (aqueous PI), 2% aqueous chlorhexidine gluconate (aqueous CG), and 0.5% alcoholic chlorhexidine gluconate (alcoholic CG).Design.Prospective, randomized controlled trial.Setting.Intensive care unit in a teaching hospital.Methods.Patients were randomly assigned to 1 of the 3 skin antisepsis groups. The distal tips of catheters were semiquantitatively cultured when the catheters were no longer necessary or if there was a suspicion of catheter-related infection. Rates of catheter colonization, catheter-related sepsis, and catheter-related bacteremia were compared among the 3 groups.Results.A total of 631 catheters were included in the study (194 from the aqueous PI group, 211 from the aqueous CG group, and 226 from the alcoholic CG group). The incidence of catheter colonization was significantly lower in the alcoholic CG than in the aqueous PI group (14.2% vs 24.7%; relative risk, 0.5 [95% confidence interval, 0.3-0.8; P< .01]); it was also significantly lower in the aqueous CG group than in the aqueous PI group (16.1 % vs 24.7%; relative risk, 0.6 [95% confidence interval, 0.4-0.9; P= .03]). There were no significant differences between the aqueous CG and the alcoholic CG groups. Incidences of catheter-related bacteremia were similar for all 3 groups. The aqueous and alcoholic CG solutions were superior to the aqueous PI solution in preventing catheter colonization due to gram-positive bacteria.Conclusions.The aqueous and alcoholic CG solutions for cutaneous antisepsis were similarly effective in preventing colonization of central venous catheters and arterial catheters. Both had significantly lower incidences of colonization than did the aqueous PI solution; this effect seems to be related to the CG solutions' more efficacious prevention of colonization with gram-positive bacteria.

The objectives of this study were to determine the incidence of precocious puberty and effect of exposure to a bull on the incidence of precocious puberty in beef heifers. The experiment was conducted using 120 heifers during 1990 and 1991. Heifer calves were randomly assigned to be pastured in the presence (n = 30 heifers/yr) or absence (n = 30 heifers/yr) of a bull starting at 140 ± 14 d of age for the duration of the study. Heifers were 402 ± 14 d of age at the time the study was completed. Blood samples were collected weekly to determine the age of onset, duration and cessation of luteal function. Heifers were considered to have exhibited a precocious puberty when the onset of luteal function was before 300 d of age. There was no effect of exposure to a bull on the incidence of precocious puberty, and therefore the data were pooled. The incidence of precocious puberty was greater (P< .02; X2= 5.5) in 1990 (25.0%; 15 of 60) compared with 1991 (8.3%; 5 of 60). There was no effect of year on age of precocious puberty (194 ± 12.4 d of age), duration of cyclic luteal function (65 ± 10.5 d), or the age at resumption of anestrus (260 ± 15.3 d of age). Precocious puberty does occur in developing beef heifers; as many as 25% of heifers have transient luteal function before 300 d of age. However, exposure to a bull has no effect on the incidence of precocious puberty.

The objectives of this study were to determine whether circulating concentrations of genadotropins and gonadal hormones of boars were altered as a result of selection of pigs for size of testes or for embryonal survival and(or) number of ovulations. Included in Exp. 1 and 2 were boars with the greatest estimated paired weight of testes (TS) and boars from a control (C) line. Concentrations of FSH were similar (P> .10) in boars from the TS and C lines. In Exp. 3, 4, and 5, circulating concentrations of FSH and 17 β-estradiol (E2) were evaluated in neonates, during pubertal development, and in mature boars of lines selected for an index of number of ovulations and embryonal survival (I), and data were compared to those for boars from a respective C line. Concentrations of E2were not different in boars from the I line and those from the C line during the early neonatal period but were greater (P< .05) in boars of the C line than in those from the I line during pubertal development. Concentrations of FSH were greater (P< .05) in mature boars from the I line than in those from the C line. In summary, selection for size of testes did not influence circulating concentrations of FSH in mature boars. The secretory pattern of E2in boars before puberty changed as a result of selection for embryonal survival and number of ovulations in females of the I line, and the different patterns of circulating E2early in life may result in enhanced circulating concentrations of FSH in adult boars of the I line compared with boars of the C line.

Standard cell culture and a shell vial technique using a monoclonal antibody were compared for the detection of varicella-zoster virus in 167 mucocutaneous specimens. Of 75 specimens from patients clinically diagnosed with varicella or zoster, a total of 40 (53.3 %) were positive by either method (4 positive only by conventional culture and 4 only by shell vial). No false-positive results were obtained with shell vials stained after 48 h of incubation. This technique is rapid, 100 % specific, and should be a good alternative to cell culture. Both techniques are equally influenced by antiviral treatment or by the time of evolution of disease.